For some reason your phone's firmware is corrupted.
The best(easy) way is to reflash your phone completely. So, for your phone you need the following files:
1. MAIN firmware: W300_R9A036_MAIN_GENERIC_JE_RED49 (this is the latest here at TopSony)
2. FS: W300_R9A036_FS_EUROPE_2_RED49
3. Custom pack: Jing_Generic_CDA102665_11_R2A_Generic_Trade_EUROPE _2
Here are some tutorials for start: XS++ 2.x Guide, How to use phone sx or xs++